Cambodia is a small country with no natural resources of any kind. Even to grow rice you need diesel for tractors and fertilizers that are produced from natural gas using energy (which Cambodia lacks).
There's very few opportunities for a small country without resources.
And to grow rice you need to somehow get rid of US bombs that majority of Cambodia soil is very well fertilized with.
Between 1965 and 1973 US dropped 2,756,941 tones of bombs on 113,717 sites in Cambidia. Thats more bombs than all allies together used in all of World War II.
Tens of people still getting killed by them every year.
There's very few opportunities for a small country without resources.